The micro-apartments are designed as "crash pads for people who work 24/7 in Silicon Valley and need a place in the city to sleep and party," she said. "It doesn't build a sense of community or neighborhood."

The battle will be taken up Thursday afternoon by the Planning Commission, where the staff wants the commission to reject a Board of Supervisors plan to put a 375-unit cap on the number of new market-rate micro-apartments in the city.

"We don't see any policy rationale for the cap," said Sophie Hayward, a city planner dealing with the issue. "We need the housing."

She won't get an argument from Supervisor Scott Wiener, who introduced both the original measure to allow construction of the micro-apartments and the proposal to limit the number that can be built.

"Ideally, I'd love to move this through with no cap, but politics being what they are, I need this cap to get (the measure) past the board," he said. "This will be an opportunity to get a few projects through and see how they do. I think they will be popular."

The cap applies only to micro-units renting at market rate and not to those designed as student or group housing or as affordable units.

Most of the proposed apartments, known in some cities as efficiencies, will probably be built in the SoMa neighborhood or other densely populated parts of the city. The new 220-square-foot minimum, which includes a living room, kitchen and bathroom, would apply only to new construction.

Housing needed

For Wiener, it's a chance to expand the amount of housing in a city that desperately needs it. Just to meet its share of the Bay Area's housing requirements, the city's general plan sees a need for thousands of new residential units in upcoming years, with 60 percent of them designed for households whose incomes are extremely low, very low and moderate.

Micro-apartments "can help satisfy the demand for moderate-income housing, while freeing up space in larger, existing units ... for family housing," according to a Planning Department report.

About 40 percent of San Francisco residents live alone, Wiener said, and many others live with roommates in situations that aren't much different from the micro-units, with each effectively living in a small bedroom and sharing a living room and kitchen.

"Many of these people would be happy to pay a reasonable rent to live alone and we should offer them the opportunity," the supervisor said.

But tenant rights groups and housing advocates worry that developers could concentrate on the more profitable smaller units and ignore the city's need for family housing.

"What should be our priorities?" Shortt asked. "It's more important to build family and affordable housing than accommodate the needs of newcomers who will come here to have a little box in SoMa and then hop on the Google bus."

The proposed dwelling places are smaller than similarly styled units in places like New York City, she added, and there's no telling what effect the new apartment buildings will have on nearby rents and future construction in the city.

"It's an experiment and should be treated as such," Shortt said. "We should roll these out on a small basis and see what happens."

But Hayward, noting that the planning commissioners enthusiastically endorsed Wiener's original plan for micro-units when it came before them in June, said the Planning Department opposes the effort to meter one style of new housing.

Even if the Planning Commission rejects the idea of a cap on the micro-apartments, the board can choose to ignore that recommendation and go ahead with the proposed limits.